[vtkusers] Time support in VTK 5.X

[David C. Thompson]

Please, let's keep this on the list so that others who are interested
may benefit from it.

> ... Now, that I've got a starting point,
> I'll try and dig into the code. Nevertheless, there are some things
> which look somewhat odd to me (e.g. the fact that
> vtkStreamingDemandDrivenPipeline::TIME_STEPS is static which means there
> is exactly one per class and not per object), ...
What's static is the key, not the value. The pipeline executive creates
a vtkInformation object (a map of <key,value> pairs) for each pipeline
connection, so the same key can have different values for each data
object.

	David